The NYTimes editorial page asks the "if we build it, will they come?" question and answeres "no":
Yet for all the conditions attached to it, the multibillion-dollar aid package for Detroit’s carmakers approved by the White House (with Mr. Obama’s support) fails to address one crucial question: Who will buy all the fuel-efficient cars that Detroit carmakers are supposed to make?
The danger is that too few will, especially if gasoline prices remain low. Therefore, it might be time for the president-elect and Congress to think seriously about imposing a gas tax or similar levy to keep gas prices up after the economy recovers from recession.
And for you fiscal policy junkies:
A bitter recession is not the most opportune time to ratchet up the price of energy. But if the Obama administration is to meet its twin objectives of reducing the nation’s dependence on foreign oil and cutting its emissions of greenhouse gases, it needs to start thinking now about mechanisms to curb the nation’s demand for energy when the economy emerges from recession in the future.